I have heard that Duryodhana showed 3 fingers to Krishna after being defeated by Bhima. Lord Krishna understood his thought and told he was remembering for 3 mistakes he made... he told 1st finger: a war fort in Hastinapur should have been made in 13 yrs. 2nd finger: Vidura should have been forced not to remain as neutral and his intellect should be used 3rd finger: Aswatthama should have been made commander of army as he knew Ashwatthama was Rudra avatar... But I don't know whether this story is mentioned in Mahabharat of Vyas or not...
– TejasweeApr 19 '16 at 15:08

Did you saw Karna some days back It comes on Sony Entertainment. It showed how Duryodhan went in argue with Vidur. Duryodhan said him he was just a नीच caste. After being insulted by Duryodhan, he refused to plan battle for Duryodhan. As he was Mahamantri of Hastinapur, he could not support Pandav.
– Anubhav GoelApr 20 '16 at 1:53

1 Answer
1

First Vidura was not considered as Kshatriya and He was insulted by Duryodhana
(see below)

Lord Krsna, the Personality of Godhead, as accepted the
sons of Prtha as His kinsmen, and all the kings of the world are with
Lord Sri Krsna. He is present in His home with all His family members,
the kings and princes of the Yadu dynasty, who have conquered an
unlimited number of rulers, and He is their Lord. You are
maintaining offense personified, Duryodhana, as your infallible son,
but he is envious of Lord Krsna. And because you are thus maintaining
a nondevotee of Krsna, you are devoid of all auspicious qualities.
Relieve yourself of this ill fortune as soon as possible and do good
to the whole family! While speaking thus, Vidura, whose
personal character was esteemed by respectable persons, was insulted
by Duryodhana, who was swollen with anger and whose lips were
trembling. Duryodhana was in company with Karna, his younger brothers
and his maternal uncle Sakuni. Who asked him to come here,
this son of a kept mistress? He is so crooked that he spies in the
interest of the enemy against those on whose support he has grown up.
Toss him out of the palace immediately and leave him with only his
breath. Thus being pierced by arrows through his ears and
afflicted to the core of his heart, Vidura placed his bow on the door
and quit his brother’s palace. He was not sorry, for he considered the
acts of the external energy to be supreme. By his piety,
Vidura achieved the advantages of the pious Kauravas. After leaving
Hastinapura, he took shelter of many places of pilgrimages, which are
the Lord’s lotus feet. With a desire to gain a high order of pious
life, he traveled to holy places where thousands of transcendental
forms of the Lord are situated. He began to travel alone,
thinking only of Krsna, through various holy places like Ayodhya,
Dvaraka and Mathura. He traveled where the grove, hill, orchard, river
and lake are all pure and sinless and where the forms of the Unlimited
decorate the temples. Thus he performed the pilgrim’s progress.